tiple lines of evidence have demonstrated that the flagellar axoneme anchors components of a signaling machinery that regulates the axonemal dyneins and ultimately flagellar motility. Important to this process is the phosphorylation of the 11-dynein isoform. Critical for control, the key enzymes involved in modifying 11 are physically anchored in the axoneme. Of these, casein kinase 1 (CK1) is proposed to be anchored at the base of the 11 complex, where it is in a key position to phosphorylate 11 and regulate 11 dynein activity (Yang and Sale, 2000). Inherent to this process is the proper assembly and anchoring of 11, so that it is the correct position to receive the signals from the signal transduction machinery. Thus the most important questions include how 11 and CK1 are anchored to the axoneme. The 11 subunit, intermediate chain (IC)97, has been recently cloned and determined to be a novel dynein 1C. Using Chlamydomonas as a model system, the proposed research is designed to characterize the newly identified IC97 component of the 11 complex and to determine its role, along with the other ICs, in 11 assembly and function.